Problem with the reference to (CTreeCtrlEx)

I have an MFC dialog which has a Tree(CTreeCtrlEx) structure where each node is a combo box.
I want to have a "Cancel" button which will cancel the option chosen by the user and goes with
the user chosen previosly.I have a cancel button but,as soon as the user changes the (CTreeCtrlEx)
item,the values will be changed.

Now all i want is to store the previous option and compared to DoModal return.and use the oprions
accordingly.

Currently, i am doing like this ,i have mentioned below
OC_Dlg_PureMFC_Test_Options_c is a subclass of CTreeCtrlEx

Code:

OC_Dlg_PureMFC_Test_Options_c(m_Options).DoModal(); // m_Options is a reference...

How will i save the previous m_Options?....Any idea?
I tried doing the following ...